Resistance exercise training has been shown to have a positive effect on strength and functional status in the elderly (4). However, an acute bout of resistance exercise causes muscle soreness and may lead to transitory insulin resistance. Insulin increases skeletal muscle glucose disposal, which is studied with stable isotopically labeled glucose and mass spectrometry. Aging is often associated with the development of insulin resistance, hyperinsulinemia, diabetes mellitus and coronary artery disease. The extent to which aging per se is responsible for these health problems is not clear, as a decline in physical activity and changes in body composition can also be major contributing factors. Data from this project will provide information on the extent to which basal and glucose-stimulated insulin action can be affected by resistance exercise which causes muscle soreness in young and older men and women. The results from this study can contribute to understanding the m echanism by which exercise can impact metabolic control in the elderly.